2-Chloro and alkoxy or alkylthio substituted esters useful for the control of insects

ABSTRACT

Novel olefinic unsaturated esters substituted at C-2 with chloro, hydroxy, acyloxy, oxo or amino, syntheses of Alpha , Beta -unsaturated esters, intermediates therefor and the control of insects.

United States Patent 11 1 1111 3,887,594 Henrick June 3, 1975 Z-CHLOROAND ALKOXY OR ALKYLTHIO [56] References Cited SUBSTITUTED ESTERS USEFULFOR THE UNITED STATES PATENTS CONTROL OF INSECTS 3,277,147 10/1966Machleidt 61 al 260/468 [75] inventor; Clive A, Henrick, P310 Alto Calif3,657,291 4/1972 Jarolim et al. 260/408 3,666,780 5/l972 Calame et al260/405 slg eez Zoewn Corporation, a Alto, 3,803,187 4 1974 Henrick260/408 Calif.

[22] Filed: Jan. 14, 1974 Primary ExaminerDonald G. Daus AssistantExaminerDiana G. Rivers [2]] Appl' N05 433,411 Attorney, Agent, orFirmLee-Louise H. Priest;

Related us. Application Data Donald Erickson [62] Division of Ser. No.205,344, Dec. 6, 1971, Pat. No.

3,803,187. ABSTRACT Novel olefinic unsaturated esters substituted at C-2[52 us. (:1. 260/408; 260/3 99;260/D1G. 44 with mom, hydroxy, acyloxy,OX0 or amino, gym- 51 l t. c1. C07C 69/62; A0111 9/24 Ses of a,fiunsaturated esters, intermediates h f [58] Fleld or Search 260/DIG.44, 408, 410.9 R, and the control of insects 6 Claims, N0 DrawingsZ-CHLORO AND ALKOXY OR ALKYLTHIO SUBSTITUTED ESTERS USEFUL FOR THECONTROL OF INSECTS This is a division of application Ser. No. 205,344,filed Dec. 6, 1971, now US, Pat. No. 3,803,187.

This invention relates to novel compounds, intermediates therefor,syntheses and the control of insects. More particularly, the presentinvention provides novel compounds of formula A which are useful agentsfor the control of insects and valuable intermediates for thepreparation of insect control agents.

each of m and n is zero or the poistive integer one, two or three;

each of R, R, R R and R is lower alkyl;

R is hydrogen or lower alkyl;

X is chloro, hydroxy or lower acyloxy;

Z is hydrogen, lower alkyl, lower alkoxy or lower alkylthio; and

Z is hydrogen or, taken with Z, a carbon-carbon bond.

In the description hereinafter, each of m, n, R-R, R, X, Z and Z is asdefined above, unless otherwise specified.

In one embodiment of the present invention, there is provided novel2-chloro compounds of formula A which can be prepared as outlined below.

In the practice of the above synthesis, an allylic alcohol of formula 1is reacted with a chloro diester of formula II in the presence of abasic catalyst such as aluminum isopropoxide, sodium methylate,potassium methylate, sodium ethylate, sodium isopropylate, sodiumbutylate, and the like to prepare a 2-chloro ester of formula A. Thereaction is generally practiced at an elevated temperature of from about100 to 225C or higher, usually 150-200C. The. reaction is practicedutilizing molecular selves, spinning band column, or the like to removealcohol formed during the reaction. A

gas meter is often utilized to measure the evolution of carbon dioxide.Cessation of the evolution of alcohol and CO indicates completion of thereaction. Suitable procedures are described by Tavel, Helv. Chim. Acta33, No. 163, 1266 (1950) and Hoffman, et al., Ann. Chem. 729,52 (1969).

A 2-chlor0 ester of formula A can be prepared also by the reaction of anallylic alchol of formula I with a tri-alkyl ortho chloro acetate offormula III in the presence of a catalyst such as propionic acid, 2,4-dinitrophenol, and the like at a temperature of about -200C.

A 2-chloro ester of formula A in accordance with the present inventionis dehydrochlorinated to form useful insect control agents of formula B:

The dehydrochlorination can be carried out by heating a 2-chloro esterof formula A in s-collidine, pyridine or the like at a temperature ofabout l25200C. The dehydrochlorination can be practiced also by heatinga 2-chloroester in an organic solvent such as dimethylformamide,N-methylpyrrolidone or dimethylsulfoxide in the presence of alkalineearth or alkali metal carbonate.

In another embodiment of the present invention, a 2-chloro ester offormula A is converted into a 2- acyloxy compound of formula A" (R islower acyl) which is useful for the control of insects and as anintermediate for the preparation of a,/3-unsaturated esters of formulaB.

A -acyloxy compound of formula A" is prepared from a 2-chloro ester offormula A by reaction of an alkali-metal carboxylate such as potassiumacetate, potassium propionate, and the like in an aqueous alcohol suchas aqueous ethanol. The reaction is conducted at a temperature of fromabout 0-25C. A Z-aCy Y compound of formula A on pyrolysis provides ana,B-unsaturated ester of formula B. A suitable procedure for pyrolysisof the 2-acyloxy compounds is debed by Greenwood, J. Org. Chem. 27, 2308(1962)- The pyrolysis is conducted by using oxygen-free nitrogen toCarry the 2-acyloxy compound through a py ysis tube with the helices ata temperature of about 100-500C.

In another embodi f the present invention, there is provided novel2-hydroxy-compounds of fOrmula A (X is hydroxy) which are prepared bymild hydrolysis of a Z-acyloxy compound of formula A" usmg potassiumcarbonate, potassium bicarbonate or other base in aqueous alcohol suchas aqueous methanol,

anol, and the like. The reaction is conducted at a temperature of about20C. The 2-hydroxy compounds of formula A, in addition to their utilityas insect control agents, serve as precursors for the preparation ofnovel 2-oxo compounds of formula IV which are active agents for thecontrol of insects.

The oxidation of a 2-hydroxy compound of formula A to a 2-oxo compoundof formula IV can be accomplished using an oxidizing agent such aschromium trioxide-2 pyridine complex in methylene dichloride at about 0.An excess of the chrominum trioxide-pyridine complex is used. Theoxidation can be accomplished also by use of manganese dioxide inchloroform for several hours. During the oxidation, if Z represents alower alkythio group in the precursor (A wherein X is hydroxy), it isoxidized to a lower alkylsulfonyl group In another embodiment of thepresent invention, there is prepared novel 2-amino compounds of formulaV which are useful for the control of insects (each of R and R ishydrogen or lower alkyl).

The 2-amino compounds of formula V are prepared by the reaction of a2-chloro ester of formula A with an excess of amine in an organicsolvent such as an ether solvent or hydrocarbon solvent at lowtemperature such as about 0.

The starting material of formula I can be prepared by the reaction of analdehyde of formula V1 with a Grignard of a halide of formula VII (X isbromo, chloro or iodo) using conventional Grignard methods.

(VI) l R1-CH=CH-X' v11 The aldehydes of formula VI are described inapplications Ser. No. 187,897, filed Oct. 8, 1971; Ser. No. 187,898,filed Oct. 8, 1971, now US. Pat. Nos. 3,755,411 and 3,752,843,respectively; and Ser. No. 201,189, filed Nov. 22, 1971 now abandoned,the disclosures of which are incorporated by reference.

The compounds of the present invention of formula A, IV and V are usefulfor the control of insects. The utility of these compounds as insectcontrol agents is believed to be attributable to their juvenile hormoneactivity. They are preferably applied to the immature insect in view oftheir effect on metamorphosis and otherwise cause abnormal developmentleading to death or inability to reproduce. Typical insects on which thecompounds of the present invention are active include Hemipteran such asLygaeidae and Miridae; Coleopteran such as Tenebrionidae andDermestidae; Lepidopteran such as Pyralidae and Gelechiidae; Dipteransuch as mosquitoes and flies; Homopteran such as aphids; and otherinsects. The compounds of the present invention can be applied at lowdosage levels of the order of 0.01 rig. to 25.0 ,ug. per insect.Suitable carrier substances include liquid or solid carriers, such aswater, acetone, xylene, mineral or vegetable oils, talc, vermiculite,natural and synthetic resins and silica. Treatment of insects inaccordance with the present invention is accomplished by spraying,dusting or exposing the insects to the vapor of the compounds of formulaA. Generally, a concentration of less than 25 of the active compound isemployed. The formulations can include insect attractants, emulsifyingagents or wetting agents to assist in the application and effectivenessof the active ingredient.

The term lower alkyl, as used herein, refers to an alkyl group, branchedor straight, having a chain length of one to six carbon atoms. The termlower alkoxy refers to an alkoxy group of one to six carbon atoms suchas methoxy, ethoxy, isopropoxy, and the like. The term lower alkylthiorefers to an alkylthio group of one to six carbon atoms such asmethylthio, ethylthio, isopropylthio, and the like. The term loweracyloxy refers to a hydrocarbon carboxylic acyloxy group of one to sixcarbon atoms such as acetoxy and isopropionoxy.

The following examples are provided to illustrate the present invention.Temperature is given in degrees Centigrade.

EXAMPLE 1 To a mixture of 12.7 g. of 6,10-dimethylundec-2-en- 4-ol and13.0 g. of diethyl 2-chloromalonate is added 0.02 g. of aluminumisopropoxide. The reaction mixture is heated under a spinning bandcolumn at 170l80 with continous removal of ethanol as it forms. Thereaction is continued until evolution of carbon dioxide ceases andsubstantially all ethanol is removed. After cooling, the crude productis fractionally distilled to yield ethyl-2-chloro-3,7,1l-trimethyldodec- 4-enoate.

EXAMPLE 2 A solution of 19.8 g. of 6,l0-dimethylundec-2-en-4- 01, 25.2g. of diethyl 2-chloromalonate and 0.27 g. of sodium methylate is heatedat l-200 with continous removal of ethanol. The reaction is continueduntil ethanol is removed and evolution of carbon dioxide stops. Aftercooling, ether is added and the mixture washed with water and dried.Ether is removed under reduced pressure and the concentrate fractionallydistilled to give ethyl 2-chloro-3,7,l l-trimethyldodec-4- enoate.

EXAMPLE 3 Each of di-isopropyl 2-chloromalonate and dimethyl2-chloromalonate is reacted with 6,10-dimethylundec- 2-en-4-ol toprepare isopropyl 2-ch1oro-3,7,l ltrimethyldodec-4-enoate and methyl2-chlor0-3,7,l1- trimethyldodec-4-enoate, respectively.

EXAMPLE 4 A mixture of g. of ethyl2-chloro-3,7,1ltrimethyldodec-4-enoate and 1.5 molar equivalents ofs-collidine is heated at l50-l70 for about 2 hours. After cooling, etheris added and the mixture washed with cold dilute hydrochloric acid,brine and aqueous sodium bicarbonate. The mixture is dried over sodiumsulfate, ether evaporated and the concentrate fractionally distilled togive ethyl 3,7,1l-trimethyldodeca-2,4- dienoate.

EXAMPLE 5 A solution of 10 g. of ethyl 2-chloro-3,7,11-trimethyldodec-4-enoate, 100 ml. of dimethylformamide and one g. ofpotassium carbonate is heated at l0O-l15 for about 2 hours. Aftercooling, ether is added followed by water. The organic phase isseparated, washed with water and brine, dried and evaporated to yieldethyl 3,7,1l-trimethyldodeca-2,4- dienoate which is purified byfractional distillation.

EXAMPLE 6 EXAMPLE 7 A mixture of one gram of ethyl 2-acetoxy-3,7,11-trimethyldodec-4-enoate, 1.5 molar equivalents of potassium carbonateand ml. of aqueous ethanol (1:4)

is stirred at 1520 until hydrolysis of the acetate is complete asfollowed by thin layer chromatography. Then the mixture is diluted withwater followed by extraction with ether. The combined ether extracts arewashed with water, dried over calcium sulfate and evaporated to yieldethyl 2-hydroxy-3,7,l1- trimethyldodec-4-enoate which can be purified bychromatography.

EXAMPLE 8 Using the procedure of Greenwood, J. Org. Chem. 27, 2308 (July1962), ethyl 2-acetoxy-3,7,l ltrimethyldodec-4-enoate is pyrolyzed usinga tube maintained at 400 and passage of the ester by flow of oxygen-freenitrogen to provide a residence rate in the tube of 3.5 seconds. Thepyrolysate is taken up in pentane, washed with water and brine quickly,and solvent evaporated to give crude ethyl 3,7,1 l-trimethyldodeca-2,4-dienoate which is purified by fractional distillation.

EXAMPLE 9 A mixture of 3 g. of ethyl 2-hydroxy3,7,1ltrimethyldodec-4-enoate, 1.5 molar equivalents of manganese dioxide and50 ml. of chloroform is prepared at 0, under nitrogen, by slow additionof manganese dioxide. The reaction mixture is allowed to stand for about24 hours with stirring and then is filtered. The filter cake is washedwith hexane and the combined washings and filtrate evaporated to givecrude ethyl 2- oxo-3,7,l l-trimethyldodec-4-enoate which can be purifiedby chromatography.

EXAMPLE 10 To a solution of 6 molar equivalents of chromium trioxide-2pyridine complex in ml. of methylene dichloride, under nitrogen and at0, is added a solution of 4.0 g. of ethyl 2-hydroxy-3,7,ll-trimethyldodec-4- enoate in methylene dichloride. After addition iscomplete, the mixture is stirred one hour at 0 and then poured into sat.sodium bicarbonate and extracted with methylene chloride. The combinedmethylene dichloride extracts are washed with water and brine, driedover calcium sulfate and evaporated under reduced pressure to give ethyl2-oxo-3,7,l l-trimethyldodec-4- enoate which can be purified bychromatography.

EXAMPLE 1 l A mixture of 3 g. of ethyl 2-chloro-3,7,lltrimethyldodec-4-enoate, 2.4 molar equivalents of diethylamine and 60ml. of ether is stirred overnight (about 17 hours) at 0. The mixture isthen washed with water, dried over calcium sulfate and evaporated underreduced pressure to yield ethyl 2-diethylamino-3,7,l 1-trimethyldodec-4-enoate.

EXAMPLE 12 Five grams of ethyl 2-chloro-3,7,l l-trimethyldodec- 4-enoateand 50 ml. of benzene, cooled to 5, is saturated with ammonia. Themixture is then stirred for 8 hours while maintaining dry conditions.After the mixture is warmed to room temperature, it is washed withdilute sodium hydroxide and then evaporated under reduced pressure toyield ethyl 2-amino-3,7,l 1- trimethyldodec-4-enoate.

EXAMPLE 13 A mixture of 9.0 g. of 6,10-dimethylundec-2-en-4-ol, 42 g. oftriethyl orthochloroacetate, and 0.36 g. of propionic acid is preparedand then refluxed under a spinning band column to remove ethanol as itforms. After the elimination of ethanol is about complete, the crudereaction product is fractionally distilled to yield ethyl 2-chloro-3,7,1 1-trimethyldodec-4-enoate.

EXAMPLE 14 The reaction of Example 1 is repeated using an equivalentamount of each of 6,10-dimethylundeca- 2,9-dien-4-ol, l0-methoxy-6, 10-dimethylundec-2-en-4- o1, 6,10,l0-trimethylundec-2-en-4-ol and 6,9,10-trimethylundec-2-en-4-ol in place of 6,lO-dimethylundec-2-en-4-ol toprepare ethyl 2- chloro-3,7,l l-trimethyldodeca-4, l O-dienoate, ethyl2-chloro-1 l-methoxy-3 ,7,l 1-trimethyldodec-4-enoate, ethyl2-chloro-3,7,l 1 l-tetramethyldodec-4-enoate and ethyl 2-chloro-3 ,7,10,1 l-tetramethyldodec-4- enoate, respectively. Dehydrochlorination ofthe thusprepared 2-chloro-esters provides the correspondingoz,B-unsaturated esters.

EXAMPLE 15 To 12 g. of magnesium turnings in 100 ml. of drytetrahydrofuran, under argon, is added about 2.0 g. of prop-l-enylbromide. Addition of iodine initiates the reaction and then 60 g. ofprop-l-enyl bromide in dry tetrahydrofuran is added slowly. Additionaltetrahydrofuran is added to total volume of about 250 ml.

To the Grignard solution is added 78 g. of 3,7- dimethyloctan-l-alslowly, with stirring. After addition is complete, the reaction mixtureis stirred for an additional 16 hours and then about 50 ml. of sat.ammonium chloride is added and the mixture filtered. The filtrate isconcentrated under reduced pressure and then taken up in ether. Theethereal phase is washed with sat. brine, dried over magnesium sulfateand solvent evaporated to yield 6,10-dimethyl-4-hydroxyundec-2-ene.

The above reaction is repeated using an equivalent amount of each of3,7,-dimethyloct-6-en-l-al, 7- methoxy-3,7-dimethyloctan-l-al,3,7,7-trimethyloctanl-al, 3,6,7-trimethyloctan-l-al,6-methoxy-3,5,6-trimethylheptan-l-al, 3,6-dimethylheptan-l-al,6-methoxy- 3,6-dimethylheptan-l-al and 3,5,6-trimethylheptanl-al toprepare the respective allylic alcohol, i.e. 6,10-dimethyl-4-hydroxyundeca-2,9-diene, IO-methoxy- 6,1 O-dimethyl-4-hydroxyundec-2-ene, 6,10,10- trimethyl-4-hydroxyundec-2-ene4-hydroxy-6,9, l O- trimethylundec-Z-ene, 9-methoxy-4-hydroxy-6,8,9-trimethyldec-Z-ene, 6,9-dimethyl-4-hydroxydec-2-ene,9-methoxy-4-hydroxydec-2-ene and 6,8,9-trimethyl-4- hydroxydec-2-ene.

EXAMPLE 16 A mixture of 23 g. of lithium propynylide and 350 ml. ofabsolute dimethylformamide is cooled in an icebath. To the cooledmixture is added a solution of 30 g. of 3,7-dimethyloctan-l-al and 150ml. of dimethylformamide slowly. The reaction mixture is allowed tostand overnight (about 16 hours) and then 250 ml. of ammonium chloride(2N) is added followed by extraction with ether. The combined etherextracts are concentrated under reduced pressure to remove solvent. Thecrude product (6,lO-dimethylundeca-2-yn-4-ol) can be purified byspinning band distillation.

Synthetic quinoline (21 drops) and 4.5 g. of Lindlar catalyst are addedto 14.0 g. of 6,10-dimethylundeca-2- yn-4-ol in 150 ml. of pentane(purified over permanganate) and the system evacuated and filled withhydrogen. The alkyne absorbs about 1.5 liters of hydrogen at roomtemperature before starting material disappears as indicated by gaschromatography. Celite is added to the mixture and then filtered. Thefiltrate is washed with 2N sulfuric acid to eliminate quinoline. Theorganic layer is washed with water and sat. brine, dried over calciumsulfate and evaporated to give 6, 1 O-dimethylundec-2--en-4-0l which canbe purified by chromatography.

By use of the process of this example, other aldehydes of formula VI canbe converted into the respective allylic alcohol of formula EXAMPLE 17Citronellal g-) in ether (50 ml.) is slowly added at to a solution oflithium propenylide (prepared from 32.5 g. of propenyl bromide and 3.45g. of lithium in 500 ml. of ether according to the method of Braude andColes, J. Chem. Soc. p. 2078, 1951). After addition is complete, thereaction mixture is stirred overnight (about 18 hours) and then 250 ml.of sat. aqueous ammonium chloride is added. The mixture is filtered andthe ether layer separated, dried and evaporated to give6,10-dimethylundec-2-en-4-ol which can be purified by distillation orchromatography.

The process of this example can be used to prepare other allylicalcohols of formula 1 from the aldehydes of formula VI.

Propenyl lithium can be prepared also by the method of Seyferth andVaughan, J. Am. Chem. Soc. 86, 883 (1964).

EXAMPLE 18 Using the procedure of Example 1 or 2, each of10-methylthio-6, l O-dimethylundec-2-en-4-ol, l0-ethylthio-6,lOdimethylundec-2-en-4-ol, l0-ethoxy-6, l O-dimethylundec-2-en-4-ol,l0-methoxy-6, l O-dimethyldodec-2-en-4-ol, and6,10-dimethyldodec-2-en-4-ol is converted into ethyl 1l-methylthio-2-chloro-3,7,1 l-trimethyldodec-4- enoate, ethyl 11-ethylthio-2-chloro-3,7,l l-trimethyldodec-4- enoate, ethyl enoate,ethyl l l-methoxy-2-chloro-3 ,7,1 l-trimethyltridec-4- enoate, and ethyl2-chloro-3,7,1 l-trimethyltridec-4-enoate, respectively.

l l-ethoxy-2-chloro-3,7,l l-trimethyldodec-4- EXAMPLE 19 EXAMPLE 20 Eachof the 2-acetates of Example 19 is cOfl -f into the corresponding2-hydroxy compound listed below by mild hydrolysis using potassium carboethyl 2-hydroxy-3 ,7,l l-trimethyldodeca-4, 1 O-dtenoat ethyl2-hydroxy-l l-methoxy-3 ,7,l l-trimethy enoate ethyl 2-hydroxy-3,7,l l,l 1-tetramethyldodec-4-enoat ethyl 2-hydroxy-3 ,7, l 0,1l-tetramethyldomic- EXAMPLE 21 Following the process of either Example 9or 10, each of the Z-hydroxy-compounds of Example is oxidized to the2-oxo compound below. ethyl 2-oxo-3 ,7,l l-trimethyldodeca-4,lO-dienoate ethyl 2-oxo-l l-methoxy-3 ,7,l l-trimethyldodec-4- enoateethyl 2-oxo-3,7,l l,l l-tetramethyldodec-4-enoate ethyl 2-oxo-3,7,10,11-tetramethyldodec-4-enoate ethyl 2-oxo-l l-methylsulfonyl-3 ,7,ll-trimethyldodec- 4-enoate ethyl 2-oxo-l l-ethylsulfonyl-3,7,l1-trimethyldodec-4- enoate ethyl 2-oxo-l l-ethoxy-3 ,7,ll-trimethyldodec-4-enoate ethyl enoate ethyl 2-oxo-3,7,l1-trimethyltridec-4-enoate isopropyl 2-oxo-3 ,7,l1-trimethyldodec-4-enoate isopropyl 2-oxo-1 l-methoxy-3 ,7,ll-trimethyldodec-4- enoate 2-oxo-1 1-methoxy-3,7,l 1-trimethyltridec-4-ethyl 2-ethylamino-3,7,10,l 1-tetramethyldodec-4- enoate ethyl2-ethylamino-1 l-methylthio- 3 ,7 ,1 l-trimethyldodec-4-enoate ethylZ-ethylamino-l l-ethylthio-3,7,l l-trimethyldodec-4-enoate ethylZ-ethylamino-l l-ethoxy-3,7,l l-trimethyldodec- 4-enoate ethylZ-ethyIamino-l l-methoxy-3,7,l l-trimethyltridec-4-enoate ethyl2-ethylamino-3,7,l l-trimethyltridec-4-enoate In the same way, there isprepared isopropyl 2- ethylamino-3,7,ll-trimethyldodec-4-enoate andisopropyl Z-ethylamino-l 1-methoxy-3 ,7, 1'1 -trimethyldodec-4-enoatefrom the 2-chloro precursor.

By reacting isopropylamine, diethylamine or methylethylamine with eachof the 2-chloro compounds of formula A such as the Z-chloro compounds ofExamples l4 and 18, the respective 2-isopropylamino, 2- diethylamino and2-methylethylamino compounds of formula V are prepared, e.g. ethyl2-isopropylamino- 1 l-methoxy-3,'7,l 1-trimethyldodec-4-enoate, ethyl 2-diethylamino-l l-methoxy-3 ,7,l l-trimethyldodec-4- enoate and ethyl2-methylamino-ll-methoxy-3,7,l1- trimethyldodec-4-enoate.

What is claimed is: 1. A compound selected from those of formula (A):

4 i R c-cn (crr CH2 CH-- CH2CH-CH-CH ewe-012 (A) wherein, n is zero orthe positive integer one;

R is methyl; each of R R and R is methyl or ethyl; R is hydrogen ormethyl; R is lower alkyl; and Z is lower alkoxy or lower alkylthio.

EXAMPLE 22 ethyl 2-ethylamino-3,7 ,1 l-trirnethyldodeca-4,10- dienoate Iethyl 2-ethylamino-l l-methoxy-3 ,7,l l-trimethyldodec-4-enoate ethyl2-ethylamino-3 ,7,1 1,1 1-tetramethyldodec-4- enoate 2. A compoundaccording to claim 1 wherein R is lower alkyl of one to three carbonatoms.

3. A compound according to claim 2 wherein Z is methoxy or methylthio.

4. A compound according to claim 3 wherein n is one, R is hydrogen, andeach of R, R and R is methyl.

5. A compound according to claim 4 wherein R is methyl, ethyl orisopropyl.

6. The compound, ethyl 2-chloro-11-methoxy-3,7,1l-trimethyldodeca-4-enoate, according to claim 5.

1. A COMPOUND SELECTED FROM THOSE OF FORMULA (A):
 1. A compound selectedfrom those of formula (A):
 2. A compound according to claim 1 wherein Ris lower alkyl of one to three carbon atoms.
 3. A compound according toclaim 2 wherein Z is methoxy or methylthio.
 4. A compound according toclaim 3 wherein n is one, R14 is hydrogen, and each of R2, R3 and R4 ismethyl.
 5. A compound according to claim 4 wherein R is methyl, ethyl orisopropyl.